The present invention relates to a vacuum-tight or airtight reaction vessel having a lining of refractory material for immersion in steel-processing ladles, especially for processing steel pursuant to the vacuum circulation process; the reaction vessel includes an upper vessel part, a lower vessel part, and immersion pipes, with these parts being interconnected via flange rings and clamping mechanisms that pull the latter together.
When steel is processed pursuant to the vacuum circulation process, the reaction vessel, along with its immersion pipes, is immersed in the ladle, which is filled with molten steel, and an appropriate vacuum is set in the reaction vessel. By introducing conveying gas, a circulation of the molten steel is effected from the ladle, over the immersion pipes, and through the reaction vessel. Due to the varying stress on the refractory lining of the reaction vessel caused thereby, the intake portion (immersion pipes) and the lower and/or upper parts of the vessel must respectively be replaced after varying service lives.
When changing or replacing parts of the vessel, the problem arises, in the region of the plane of separation between the individual parts, of on the one hand providing a good airtight seal, and on the other hand at the same time providing a seal-shifted refractory lining. With heretofore known reaction vessels, the airtight seal is provided by flanges located on the outside of the vessel parts and subjected to an appropriate clamping pressure via clamping mechanisms; in the interior, the planes of separation between the vessel part linings, which generally comprise different refractory materials, are provided with a mortar.
Although after it is applied the refractory lining is subjected to a preheating and hence is preliminarily dried, during the course of further heating the reaction vessel to the required operating temperature, the generally basic refractory linings are suitable for relatively strong thermal expansion that leads to a significant expanding stress of those flanges of the vessel parts that are connected by the clamping mechanisms. Thus, the heretofore known reaction vessels have the drawback that either the connections are not adequately sealed, where too great of a gap is left between the linings of the vessel parts in the region of the plane of separation, or the airtight seal in the region of the main flanges cannot be adequately ensured due to the great expansion pressure originating from the refractory lining.
With a view toward reducing leaks and poor seals, further vessel constructions are known where the reaction vessel is embodied as a continuous steel body; if with such reaction vessels repair of the refractory inner lining is necessary, the vessel must first be cut open at the affected location in order to be able to carry out an operation on the inside of the vessel. After the repair work is concluded, the individual parts of the vessel must again be welded together. A considerable amount of expense is connected with such a process, and in addition there is the further drawback that the weld seams represent weak points during the rest of the working service of the vessel.
Pursuant to another known feature of such reaction vessels, the previously mentioned known flange connections between the parts of the vessel are securely welded to one another instead of interconnecting these parts with clamping mechanisms. This measure also results in the drawback that when the vessel parts are separated from one another in order to carry out repair operations on the inside of the vessel, the weld connections at the flanges are broken open, and must be replaced by new weld seams after the repair work is concluded. Repeated repair of parts of such reaction vessels, in addition to the high costs, also presents the danger that the many weld seams cannot withstand the stresses acting thereon.
It is therefore an object of the present invention to improve the reciprocal sealing of the parts of a reaction vessel of the aforementioned type in such a way that an airtight fit of the flanges results under all operating conditions.